It is known in the art to provide a permanently installed roll bar that spans the entire width of the vehicle (EP 0 233 777), or to assign a permanently installed roll bar to each seat (DE 196 04 423). Both solutions rely upon a so-called fixed roll bar, that is, a roll bar that does not actively deploy when a rollover threatens, that is, a roll bar that does not deploy from a stored, rest position to an upright, support position. From the German patent DE 600 01 224 T2, it is known to equip a fixed roll bar, attached to the vehicle seat, with two support positions of differing heights: a somewhat lower position when the folding vehicle roof is closed and a raised position when the folding vehicle roof is open. This is achieved in each case by means of a folding roll bar having two frame supports, pin-jointed together, the free ends of the frame supports are each located on a horizontal threaded rod, are longitudinally slideable, and are connected with the vehicle roof adjustment.
In this known construction, there is no stored position for the roll bar as there is an active system; rather, it comprises a fixed, permanently deployed roll bar with two support positions of different heights. Spatial conditions do not allow for a stored position in this construction.
One finds ever increasing numbers of constructive designs for so-called active roll bars on the market. In the case of active roll bars, the roll bar is stored in the normal, stored position, and, in the case of danger, when threatened with a rollover, the sensor-controlled roll bar is quickly deployed into a protective position. This prevents the vehicle occupants from being crushed by the rolling vehicle.
These designs typically show, for each seat, a roll bar that is U-shaped or is formed by a structural section and is guided by a guide element that is permanently attached to the vehicle. The guide element is fixed in a cassette housing. The roll bar is held in a lower rest position against the pressure of an actuating coil spring by a holding device during normal operations. In the case of a rollover, upon release of the holding device, the sensor-controlled roll bar is brought into an upper, protective position by the spring tension, whereby a locking device is actively engaged that prevents the compression of the roll bar into the cassette housing.
The holding device in this type of design typically comprises a holding element mounted on the roll bar body. The holding element stands in a releasable, mechanical connection together with a tripping element in a sensor-controlled triggering system, which is typically formed by a release solenoid, the so-called crash solenoid, or by a pyrotechnical tripping element.
The locking device, also described as a retraction block, typically comprises a pivotably coupled, spring-biased locking pawl with tooth segments and fixed toothed bar, a locking pin or the like, whereby, according to the construction, a locking element is connected with the roll bar and the other elements fixed to the vehicle.
Such a cassette construction for a roll bar protection system with a linearly deploying roll bar and with a locking pawl in the locking device is disclosed, for example, in German Patent DE 100 40 642 C1.
Other constructions for deployable roll bars are known, for example, according to German Patent DE 39 25 513 A1, the so-called swing gate, which is attached to the seat and pivots along the vehicular longitudinal axis. Also, the pivoting bar, according to German Patent DE 37 32 562 C1, which spans the vehicle width, is stored flush with the upper edge of the vehicle body in the area behind the back seats, and in the case of danger, is highly pivotal around the vehicular lateral axis.
The German Patent DE 101 43 934 A1 discloses an actively folding or collapsible roll bar, comprised of a transverse yoke roll bar, which extends at least approximately cross-wise over the width of the vehicle, and two side elements. One end of each side element is attached to the transverse yoke and can be longitudinally displaced, and the other end, under tension from a coil spring, is pivotable and connected at the vehicle body.
When the transverse yoke roll bar is in the stored, normal position, the two side elements are housed, front to front axially one behind the other in the transverse yoke roll bar. During a crash, the two side elements are deployed by the two coil springs into the protective position by the unfolding or opening of the roll bar as a whole.
This known construction of a folding roll bar is not applicable for active roll bars that are attached to the vehicle seats. The pivoting side elements lie axially one behind the other in the stored position. Because their length determines the rollover direction, they have to have a predetermined length, whereby the length of both side elements together would exceed the width of a roll bar that is attached to a vehicle seat.
Further, the known construction of a folding roll bar using the three-part conception—two side elements and a transverse yoke—is relatively expensive.